This invention relates to a portable monitor for tracking a source of radiation. More specifically this invention relates to a portable highly-sensitive radioactive source tracking system.
Current devices for radioactive source detection exist but their capabilities do not include a precise identification of the position of the source nor its movement. Data collection is independent, not correlated, and not stored. There are currently no systems which integrate signals from multiple sensors or which provide directional information or discrete source location information. In addition, prior systems allow a target to know that they are being tracked.
These prior art devices tend to be limited with respect to the range of geometrical configurations in which they can be deployed. Generally, they must be deployed in a single fixed geometrical arrangement of detectors and thus are limited to applications where the flow of traffic can be directed to meet the spatial requirements imposed by the detection device. This generally involves defining a surveillance pathway and having to alter the free flow of traffic so it is directed into the pathway. However, there is a need for a device capable of monitoring applications where the venue is defined by pre-existing boundaries such as walls or other barriers.
In particular, there are three deployment scenarios for which state-of-the-art methods are insufficient and can be significantly improved. The first scenario involves source interception along primary transportation corridors leading into major metropolitan centers. Choke points (such as rest stops, toll collection plazas, truck stops, weigh stations, and bridges) are logical hosting points where one could take advantage of existing infrastructure and visual clutter and where reduced traffic speed improves counting statistics. Since, presumably, these sites would not be among the intended site of ultimate dispersal and since the purveyor would be unaware that he has been detected, the element of surprise would exist. The second scenario involves source interception at border crossings and at maritime ports of entry in the plaza where traffic first congregates before being funneled into parallel lanes already equipped with deterrent-based portal monitors. An early-warning signal in advance of a signal from the existing system would provide increased response time. The third scenario involves personnel and small package monitoring i.e. mass transit stations, convention centers, stadiums, and airports. The tracking system could also be integrated with mobile systems with appropriate technology.
Thus, there is a need for a source tracking system which 1) detects the introduction of a source into the monitored area, 2) tracks its position in the monitored area, and 3) identifies the type of radioisotope and the source strength. These capabilities need to be provided in a way that minimizes the probability of false positives and the probability of a missed positive (false negative). In addition, for reasons related to equipment portability and cost, this must be achieved in environments where the signal-to-noise ratio may be lower than previously achievable.